This invention relates generally to apparatus for cleaning pulp suspensions. More particularly, the present invention relates to screens for cleaning pulp suspensions process for manufacturing screen of this kind
Various types of screen are known. For example WO 98/14658 discloses a screen which comprises a number of rods and supporting elements, where the supporting elements have slots. In this case the supporting elements take the shape of a U-shaped profile, which means that part of these rods must undergo plastic deformation in order to secure the rods to the supporting elements. A different kind of screen is known from DE 44 35 538 A1 which discloses rods secured with positive locking by clamping due to plastic deformation of the rod-supporting elements. In addition flat or cylindrical (centripetal or centrifugal) screens are known, where the rods are attached by welding to the rod-supporting elements. This form of fastening, however leads to a series of disadvantages because considerable welding stress is transferred to the components during welding and this causes distortion of the entire screen body. Furthermore, the fastening effect is not always guaranteed because the welds may begin to break up under certain circumstances and in the course of time due to signs of wear. The manufacturing process itself is actually very complicated and time consuming, and it Is very difficult in particular to set the supporting width precisely between two adjacent screen rods.